Sinclair ZX Spectrum +2 RGB to SCART Problem

I'm using a cable from Retro Computer Shack: www.ebay.co.uk/itm/260949446667
I don't think it's a sync issue since the left edge of the image is perfectly stable. Perhaps it's an issue with the RGB output? Picture is fine using the RF output.
I suspect it's something to do with my Panasonic TX-P37X10 plasma TV.

[@Audiosonicity]

Make your +2 (grey) RGB socket SCART Compliant: spectrumforeveryone.com/technical/making-your-12822a3-rgb-socket-scart-compliant/